Currently the decision to proceed from bimodal devices [cochlear implant (CI) plus hearing aid (HA) in the opposite ear] to bilateral CIs for pediatric patients is made in the absence of empirically driven guidelines. Through these research studies we will examine a continuum of residual hearing levels and length of hearing aid use by examining children with bimodal devices and two CIs. Perception of stress, pitch and prosody (suprasegmental cues) are early precursors that enable normal hearing (NH) infants to discern phonemes and ultimately perceive words. Although CIs support high levels of phoneme discrimination necessary for word recognition, the contribution of suprasegmental listening that bootstraps language development in normal hearing children may be lacking, partly due to reduced spectral resolution of current CIs. We seek to elucidate the reported benefits of early HA use for speech perception and language skills by examining a longitudinal cohort of 100 children tested when they are between 5 and 8 years and retested two years later when they are between 7 and 10 years. A continuum of early acoustic experience will be represented by children with varying degrees of residual hearing (aided thresholds) and varying durations of HA use. Some children will be bimodal users and thus have longer periods of HA use and presumably better acoustic hearing; others will have received their second CI (2CIs) either simultaneously or at varying time intervals since their first CI, and had some prior acoustic hearing experience. We hypothesize that early acoustic experience with a HA provides the very young CI user with suprasegmental cues that lead to perception of segmental cues (Aim 1). The effects of acoustic hearing on language will be mediated by speech perception, phonological processing, word learning and memory (Aim 2). Finally we seek to determine the duration of HA use and degree of aided hearing that are optimal for language level (Aim 3). These studies will eventually guide clinicians in making informed recommendations regarding early bimodal (HA/CI) use and the timing of potential bilateral cochlear implantation.